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Chinese Journal of Chromatography
2005, Vol. 23, No. 5
Online: 30 September 2005

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A Study on Peak Compression Effect in Ion-Exchange Capillary Electrochromatography with Relaxation Theory ZHANG Weibing, JEN Jen-Fon, ZHANG Yukui 2005, 23 (5):  437-440.  Abstract ( 1832 )   [Full Text(HTML)] () PDF (123KB) ( 787 )   Due to the electric characteristics of the solute transport in capillary electrochromatography (CEC), some special phenomena might occur. An example is the peak compression effect in ion-exchange capillary electrochromatography, which cannot be explained with common chromatography theory. According to the basic model of relaxation theory, it is considered that there are “co-” and “counter-” solute flows in mobile phase and in stationary phase, the expressions of the first moment and the second center moment of profile, and column efficiency are derived by the method of Laplace transform. The relations of electrophoresis velocity, electroosmosis velocity and electric dispersion velocity are also investigated with these expressions. The results show that this new model offers a better explanation for peak compression effect on the migration behaviour of charged solute in CEC. The retention time will be shorter by peak compression effect, which is similar to a solvent gradients process. The peak compression effect is not steady, and doesn’t appear until the conditions are fitted in some special situation.

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Correlation Between Octanol-Air Partition Coefficients and Retention Parameters of Polychlorinated Biphenyls on Gas Chromatographic Columns ZHANG Qing, ZHAO Hongxia, CHEN Jiping, LIANG Xinmiao 2005, 23 (5):  441-444.  Abstract ( 2250 )   [Full Text(HTML)] () PDF (162KB) ( 705 )   Octanol-air partition coefficient (Koa) is a key descriptor for describing the partitioning of organic pollutants, especially persistent organic pollutants (POPs), between air and environmental organic phases. Thus it is necessary to determine or predict the Koa values of these compounds. A novel method was introduced to describe the quantitive relationship between the octanol-air partition coefficients and gas chromatographic (GC) retention parameters A, B values of polychlorinated diphenyls (PCBs ) which are typical persistent organic pollutants. By the correlation analysis between GC retention parameters A, B values of PCBs on DB-1, DB-5 and DB-1701 columns, and their octanol-air partition coefficients, a good linear relationship was found. The stepwise multiple linear regression was used to derive binary equations with the correlation coefficients greater than 0.99, and the standard deviations are less than 0.11. In addition, based on the 153 experimental A, B values and 56 predicted A, B values, the Koa values of the remaining 190 PCBs were predicted.

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Quantitative Relationship Between Molecular Structure of Polychlorinated Biphenyls (PCBs) and Enthalpy Change (ΔH), Entropy Change (ΔS′) in Chromatographic Process ZHANG Qing, DAI Chaozheng 2005, 23 (5):  445-448.  Abstract ( 2078 )   [Full Text(HTML)] () PDF (166KB) ( 921 )   The relationship between the rule of chromatographic retention value and molecular structure is an important part in the research of chromatographic thermodynamics. The topological index structural parameter JG and the topological index adjoining parameter LJ are put forward. Parameter JG describes the correlation of quantity and position of chlorine atoms in polychlorinated biphenyl (PCB) molecules. Parameter LJ describes the ortho-position correlation of chlorine atoms in PCB molecules. The relational expression between the PCB molecular structures and their enthalpy change (ΔH), entropy change (ΔS′) in chromatographic process was discovered. The values of enthalpy change and entropy change for about 140 kinds of polychlorinated biphenyls in chromatographic process on three stationary phases, DB-1, DB-5 and DB-1701, were determined. In comparison with ΔH and ΔS′ of the experimental data those calculated from the relational expression had the average relative deviations for ΔH and ΔS′ are 0.56%-0.97% and 0.55%-1.06%, respectively.

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Applications and Progresses of Expert System on Chromatography XU Guowang, LU Xin, KONG Hongwei, SHI Xianzhe, ZHAO Xinjie, TIAN Jing, LU Guo 2005, 23 (5):  449-455.  Abstract ( 2001 )   [Full Text(HTML)] () PDF (184KB) ( 763 )   The expert system on chromatography has achieved great advancement in the past two decades, and is playing a more and more important role in solving analytical problems of complex samples. Research results of expert system on chromatography in authors’ group are reviewed with 64 references. A brief introduction of the expert system on chromatography is presented. Applications of the expert system on chromatography are summarized in the fields of petrochemical online analysis, environmental air sample analysis, tumor diagnosis and traditional Chinese medicine analysis. The review followed the scientific foot steps in the authors’ group, starting from the development of the expert system on gas chromatography, to the selection of multi-column systems in online industrial gas chromatographs in petrochemical plants, and to the employment of the new techniques in gas chromatography, liquid chromatography and capillary electrophoresis to solve the practical analytical problems in the nation’s scientific and economic development.

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Laboratory on a Microfluidic Chip LIN Bingcheng, QIN Jianhua 2005, 23 (5):  456-463.  Abstract ( 2693 )   [Full Text(HTML)] () PDF (304KB) ( 2166 )   The recent achievements of microfluidic chip and its applications, based on the works mainly carried out in the authors’ lab are reviewed. The chip fabrication capabilities have been extended into design and fabricate chips with higher degree of complexity in different materials, such as quartz, glass, polymethyl methacrylate (PMMA), and polydimethyl siloxane (PDMS). A set of methods for surface modification of micro-channels on such materials have been developed, which results in better reproducibility and higher efficiency in protein and peptide analysis. The use of novel materials for chip fabrication is also under investigation. A series of microfluidic workstations with integrated chip manipulation as well as laser induced fluorescence (LIF), ultraviolet (UV), electrochemical and chemiluminescence detection modules have been developed to attain the abilities of complex microfluidic control and data acquisition schemes. A single cell/single molecule imagining system was built up for dynamic analysis of molecular or cellular events too. Based on the work mentioned above, different functional units, such as membrane, monolithic, isotachophoresis (ITP) etc were set up and integrated. Glycoform separation of turkey ovalbumin in a lectin monolithic column and an electrophoresis channel was performed on an integrated microchip. And a novel technique has been developed that allows for the coupling of ITP and non-gel sieving electrophoresis for protein analysis in a single microchip and resulting in ~50 fold increase of the sensitivity in comparison with the use of gel electrophoresis only. A single molecule detection (SMD) based technique was developed for simultaneously measuring both bulk flow and near-wall flow velocity in the microchannels. And more recently, an SMD based technology was developed for observing molecular interactions at single molecule level. An ultra-rapid microchip electrophoresis method was established for simultaneous determination intracellular reactive oxygen species (ROS) and reduced glutathione (GSH) related to apoptosis and oxidative stress. In an effort to develop a novel microfluidic based drug screening platform, systematic studies on the interaction between granulocyte colony-stimulating factor (G-CSF) and sulfated oligosaccharides were carried out at both molecular and cellular levels. Doxorubicin induced apoptosis of human hepatocellular carcinoma (HepG2) was studied using the integrated microfluidic device with concentration generator. In the application phase, severe acute respiratory syndrome (SARS) diagnosis based on reverse transcription-polymerase chain reaction (RT-PCR) and microfluidic chip electrophoresis (MCE) with 18 cases, methylation analysis of the P16 gene in 159 samples of patients and references for cancer diagnosis and polymorphism analysis of angiotenigen gene in 226 patients and references with essential hypertension are described. Forty-three up to date references are cited.

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Advances in Packing Capillary Electrochromatographic Columns YOU Huiyan, PING Guichen, ZHANG Lihua, ZHANG Weibing, ZHANG Yukui 2005, 23 (5):  464-469.  Abstract ( 2131 )   [Full Text(HTML)] () PDF (170KB) ( 740 )   The columns in capillary electrochromatography can be classified into three classes: open tubular, packed and monolithic columns. The monolithic columns can be divided into three categories: organic polymer-based monolithic columns made from the polymerization of acrylamide, styrene, acrylate or methacrylate monomers, silica-based monolithic columns generally prepared by using sol-gel technology, and packed particulate-based monolithic columns. Monolithic columns are receiving quite remarkable attention and developing rapidly with a focus on monolithic stationary phases prepared from synthetic polymers. The preparation methods for various types of capillary electrochromatographic columns and their advantages and disadvantages are reviewed according to 100 research articles. In particular, recent advances in the preparation methods of monolithic columns and their applications are discussed in details.

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Screening of Antineoplastic Components in Radix et Rhizoma Rhei Using Chromatographic Fingerprints KONG Liang, BAO Yongming, YU Zhiyuan, LI Wei, CHEN Xueguo, HU Lianghai, ZOU Hanfa 2005, 23 (5):  470-476.  Abstract ( 2228 )   [Full Text(HTML)] () PDF (256KB) ( 865 )   A new strategy for screening of antineoplastic components in the traditional Chinese medicine of Radix et Rhizoma Rhei has been developed using chromatographic fingerprints before and after metabolism by high performance liquid chromatography-mass spectrometry. The metabolizing method was established based on the in vitro metabolism by Sprague-Dawley (SD) rat liver homogenate. By means of the metabolism methods in vitro, the antineoplastic activity of the extracts, metabolites and components of Radix et Rhizoma Rhei were determined by microculture tetrazolium （MTT） assays in vitro. It was observed that the inhibition rate of the crude extract for HeLa cell was increased from 26.7% to 36.2% after 60 min of metabolism. The changes of activities resulted from the changes of components’ structures and the bioactive components were discovered simultaneously in view of metabolism by inhibiting rate assay for the components in Radix et Rhizoma Rhei. It is concluded that the antineoplastic activity of the crude extract from Radix et Rhizoma Rhei was increased after in vitro metabolism because the antineoplastic activity of aloe-emodin, the metabolite of chrysophanol, is higher than its parent compounds.

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Separation and Identification of Isoflavonoids in Pueraria　 lobata Extracts and Its Preparations by Reversed-Phase Capillary Liquid Chromatography Coupled with Electrospray Ionization Quadrupole Time of Flight Mass Spectrometry TIAN Hongzhe, WANG Hua, GUAN Yafeng 2005, 23 (5):  477-481.  Abstract ( 2110 )   [Full Text(HTML)] () PDF (234KB) ( 1355 )   Isoflavonoids in Pueraria lobata extract and its preparations were separated and identified by reversed-phase capillary liquid chromatography (RP-CapLC) coupled with photodiode array (PDA) detector and negative electrospray ionization quadrupole time of flight (Q-TOF) mass spectrometry. The separation was performed on a 150 mm×0.32 mm i.d., 5 μm C18 capillary column, using mobile phase of 0.1% aqueous trifluoroacetic acid solution and acetonitrile containing 0.1% trifluoroacetic acid under gradient elution. The product ion spectra of the deprotonated ions allowed for the identification of puerarin, daidzin and daidzein in the sample. Puerarin was found to be the most abundant component in the extract (about 13%, mass fraction) and its preparations (19.28-24.34 mg per tablet). The structures of trace amount of unknown isoflavonoids were deduced based on the spectra of known compounds. They were proposed to be 3′-methoxypuerarin and 3′-methoxydaidzin.

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Simultaneous Determination of Five Groups of Components in Qingkailing Injection by High Performance Liquid Chromatography with Photo Diode Array Detector and Evaporative Light Scattering Detector YAN Shikai, XIN Wenfeng, LUO Guoan, WANG Yiming, CHENG Yiyu 2005, 23 (5):  482-486.  Abstract ( 2211 )   [Full Text(HTML)] () PDF (175KB) ( 791 )   A method was established for the simultaneous quantification of nine components of five different structural types in Qingkailing injection. High performance liquid chromatography coupled with a photo diode array detector and an evaporative light scattering detector (HPLC-DAD-ELSD) was employed in the determination. Four monitoring wavelengths of 240, 254, 280 and 330 nm were set to determine nucleosides (uridine and adenosine), iridoid glucoside (geniposide), flavone glycoside (baicalin) and organic acids (chlorogenic acid and caffeic acid) respectively, and a combined evaporative light scattering detector was used to detect three steroid compounds (cholic acid, ursodesoxycholic acid and hyodeoxycholic acid). The proposed method permitted the simultaneous separation and determination of five groups of compounds in Qingkailing injection, and acceptable validation results of the precision, repeatability, stability and accuracy tests were achieved. The method was applied to the analysis of 19 Qingkailing injection samples from three different plants, and the results indicated that the method could be used as a convenient and reliable method in the multi-component determination and quality control of traditional Chinese medicines.

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Analysis of Recombinant Erythropoietin and Its Tryptic Digest by Capillary Electrophoresis and Capillary Electrophoresis-Electrospray Ionization-Mass Spectrometry Using Capillary Coated with 6,6-Ionene YU Bing, CONG Hailin, LIU Huwei, LI Yuanzong, LIU Feng 2005, 23 (5):  487-491.  Abstract ( 2105 )   [Full Text(HTML)] () PDF (207KB) ( 643 )   The microheterogeneity of recombinant human erythropoietin (rhEPO) was analyzed by capillary electrophoresis (CE) using a capillary coated with 6,6-ionene. The applicability of a volatile electrolyte for fast analysis of tryptic fragments of rhEPO with online CE-electrospray ionization-mass spectrometry (ESI-MS) was investigated, resulting in a reproducible separation of eleven rhEPO tryptic fragments within 22 min under the following conditions: running buffer 300 mmol/L acetic acid-ammonium acetate (HAc-NH4Ac), pH 4.80, separation voltage -15 kV and capillary temperature 25 ℃. The proposed method is rapid and effective, and can be used for the structural analysis of related proteins.

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Determination of Polybrominated Diphenyl Ethers in Sewage Sludge by High Resolution Gas Chromatography Coupled with High Resolution Mass Spectrometry WANG Yawei, ZHANG Qinghua, LIU Hanxia, JIANG Guibin 2005, 23 (5):  492-495.  Abstract ( 2107 )   [Full Text(HTML)] () PDF (143KB) ( 1014 )   Polybrominated diphenyl ethers (PBDEs) are a group of brominated flame retardants, which are manufactured in large quantities and widely used in a variety of consumer goods. Recently they spread ubiquitously as environmental contaminants. In order to investigate the pollution level of PBDEs in different environmental samples, a method has been established by using high resolution gas chromatography coupled with high resolution mass spectrometry (HRGC-HRMS). The method was used to analyze biosamples obtained from the international inter-calibration. The results were satisfactory by analyzing z-score figures.Then, PBDE contents in three samples of sewage sludge were investigated by the method after Soxhlet extraction and multi-layer silica gel chromatographic separation. The number of PBDEs determined was 19. From the results, we can see that the contamination level of PBDEs in the sample from Beijing was higher than those from two other areas. The method was validated and applied for the analysis of environmental samples.

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Determination of Amygdalin in Hawthorn by High Performance Liquid Chromatography Lv Weifeng, DING Mingyu 2005, 23 (5):  496-498.  Abstract ( 2032 )   [Full Text(HTML)] () PDF (117KB) ( 602 )   A suitable method for extraction of amygdalin from hawthorn has been established. At first, the lipophilic components were removed with petroleum ether by ultrasonic extraction. The amygdalin was then extracted by methanol in a Soxhlet’s apparatus. For quantitation, a high performance liquid chromatographic method was developed by using a reversed-phase C18 column, mobile phase of methanol-water (15∶85, v/v) and a detection wavelengh of 215 nm. It can be concluded that the content of amygdalin is higher in the seeds than that in the hawthorn powder without the seeds and the yield of amygdalin is higher in the hawthorn pieces than that in the hawthorn powder.

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Preparation and Evaluation of Organic-Inorganic Hybrid Silica-Based Monolithic Columns for Capillary Electrochromatography YAN Lijuan, ZHANG Qinghe, LI Tong, ZHANG Weibing, FENG Yuqi, ZHANG Lihua, ZHANG Yukui 2005, 23 (5):  499-503.  Abstract ( 2199 )   [Full Text(HTML)] () PDF (207KB) ( 1232 )   A new type of organic-inorganic hybrid porous silica-based monolithic columns was developed for reversed-phase capillary electrochromatography (RP-CEC). The monolithic columns were prepared from in situ co-condensation of tetraethoxysilane (TEOS) and phenyltriethoxysilane (PTES) precursors via a two-step catalytic sol-gel procedure in the capillary to create phenyl groups distributed throughout the silica matrix for chromatographic interaction. The functionalized monolithic stationary phase was created without additional surface derivatization. The reaction conditions for the preparation of the monolithic columns were optimized. The structure and pore size distribution of the monolithic columns were characterized by scanning electron microscopy and mercury porosimetry, respectively. The effect of water concentration on the column structure was studied, and the influence of the ratio of two precursors on the pore size distribution was also investigated. The retention behavior of polycyclic aromatic hydrocarbons on the monolithic column is discussed. Seven phenols were also separated with an average efficiency over 100000 plates/m.

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Synthesis, Characterization and Evaluation of Octadecyl Ester-Bonded Monolithic Column WANG Lijuan, YANG Gengliang, LI Xu, LI Xiaoyu, YIN Junfa, LI Zhiwei, GAO Wenhui, YANG Jing, CHEN Yi 2005, 23 (5):  504-507.  Abstract ( 2190 )   [Full Text(HTML)] () PDF (156KB) ( 1089 )   An ester-bonded monolithic silica column for reversed-phase high performance liquid chromatography was synthesized by reacting stearic acid with γ-glycidoxypropyltrimethoxysilane and coupling the intermediate product onto monolithic silica column. Characterization of the prepared column was carried out with Fourier transformation infrared spectrometry and elemental analysis. The chromatographic properties of the packing were evaluated by using benzene, biphenyl, and anthracene as samples and methanol-water as binary mobile phase. The column back-pressure and separation effect were also evaluated for fast separation. The results show that the stationary phase has satisfactory chromatographic properties and resists hydrolysis between pH=2-8, and it can be used for the fast-separation of solutes efficiently. Key words: silane coupling agent; octadecyl ester-bonded monolithic silica column; reversed-phase liquid chromatographyAntibodies as Tailor-Made Chiral Selectors: an Interdisciplinary Approach to Enantiomer Separation and DetectionHOFSTETTER Heike, HOFSTETTER Oliver (Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, Illinois 60115, USA)Abstract: It has long been known that the configurational isomers of biologically active compounds, e.g., nutrients, pesticides, and drugs, may exhibit different activities in a chiral environment such as the human body. Although the majority of drugs presently in development are chiral, analytical and preparative methods for the quantitative determination and purification of stereoisomers still lag behind. One reason is that commonly used chiral selectors for the direct resolution of enantiomers are not tailor-made for a specific analyte. The identification of suitable selectors for a particular pair of enantiomers still requires considerable experimentation and is generally demanding with regard to material, time and labor. The rational design of chiral host molecules, therefore, represents a challenge in facilitating enantiomer analysis. In this article, we describe how a combination of techniques ranging from organic synthesis to molecular biology yields antibodies of predetermined specificity and stereoselectivity that can be used as tailor-made chiral selectors for the chromatographic separation of enantiomers and their sensitive detection in immunosensors.

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Antibodies as Tailor-Made Chiral Selectors: an Interdisciplinary Approach to Enantiomer Separation and Detection HOFSTETTER Heike, HOFSTETTER Oliver 2005, 23 (5):  508-519.  Abstract ( 1975 )   [Full Text(HTML)] () PDF (424KB) ( 505 )   It has long been known that the configurational isomers of biologically active compounds, e.g., nutrients, pesticides, and drugs, may exhibit different activities in a chiral environment such as the human body. Although the majority of drugs presently in development are chiral, analytical and preparative methods for the quantitative determination and purification of stereoisomers still lag behind. One reason is that commonly used chiral selectors for the direct resolution of enantiomers are not tailor-made for a specific analyte. The identification of suitable selectors for a particular pair of enantiomers still requires considerable experimentation and is generally demanding with regard to material, time and labor. The rational design of chiral host molecules, therefore, represents a challenge in facilitating enantiomer analysis. In this article, we describe how a combination of techniques ranging from organic synthesis to molecular biology yields antibodies of predetermined specificity and stereoselectivity that can be used as tailor-made chiral selectors for the chromatographic separation of enantiomers and their sensitive detection in immunosensors.

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Determination of Osteopontin at Trace Levels by Non-Gel Sieving Capillary Electrophoresis ZHAO Jingshan, WEN Jinkun, HAN Mei 2005, 23 (5):  520-523.  Abstract ( 2123 )   [Full Text(HTML)] () PDF (158KB) ( 667 )   A method of non-gel sieving capillary electrophoresis (NGSCE) was established to determine osteopontin at trace levels. The capillary used was uncoated fused silica with a size of 57 cm×75 μm i.d. and an effective length of 50 cm. The electrode buffer was a 150 mmol/L boric acid-borate buffer containing 30 g/L polyethylene glycol 20000 (pH 10.0). Other conditions were as follows: separation voltage 23 kV; detection wavelength 214 nm; pressure of injecting sample 3.4 kPa (0.5 psi)×5 s; and column temperature 25 ℃. The NGSCE method had excellent linearity with correlation coefficient of 0.996, and reproducibility with the relative standard deviation of migration time of osteopontin less than 5%. The recovery was 95% and better, the sensitivity was 0.079 g/L. Osteopontin secreted by vascular smooth muscle cells was determined by the NGSCE method at different times after serum withdrawal, and the results were in agreement with those of Western blot method. The results indicate that NGSCE is a simple and rapid method of determining osteopontin at trace levels. This method only needs a micro-amount of sample and is easily automated.

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Determination of Bioactive Components in Semencustae by Capillary Electrophoresis with Electrochemical Detection FU Liang, CHU Qingcui, GUAN Yueqing, YE Jiannong 2005, 23 (5):  524-527.  Abstract ( 1856 )   [Full Text(HTML)] () PDF (169KB) ( 751 )   A method of high performance capillary electrophoresis with electrochemical detection (CE-ECD) has been developed for the determination of five bioactive components in Semencustae, namely rutin, hyperoside, kaempferol, p-coumaric acid and quercetin. The effects of several factors such as the acidity and concentration of the running buffer, the separation voltage, the applied potential and the injection time on CE-ECD were investigated. Under the optimized conditions, these five components can be separated in a 50.0 mmol/L borax running buffer (pH 9.0) within 19 minutes. A 300 μm diameter carbon disk electrode was used as the working electrode positioned carefully opposite to the outlet of the capillary in a wall-jet configuration at potential of +950 mV (vs. saturated calomel electrode as reference electrode, SCE). Good linear relationships were established between the peak current and concentration of analytes over two orders of magnitude. The detection limits (S/N=3) were 1.93×10-5, 3.55×10-4, 3.65×10-5, 1.73×10-5 and 1.46×10-4 g/L for rutin, hyperoside, kaempferol, p-coumaric acid and quercetin, respectively. The method has been successfully applied to the determination of these analytes in Semencustae samples after a relatively simple extraction procedure, and the assay results were satisfactory.

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Determination of Isosorbide-5-Nitrate in Human Plasma by Reversed-Phase High Performance Liquid chromatography HE Lin, YU Jiying, WU Zhengzhong, SUN Shiming 2005, 23 (5):  528-530.  Abstract ( 2183 )   [Full Text(HTML)] () PDF (125KB) ( 707 )   The method was established to determine the level of isosorbide-5-nitrate in human plasma by reversed-phase high performance liquid chromatography (RP-HPLC). The sample preparation was carried by alkalizing the plasma sample followed by extraction with dichloromethane. The HPLC analysis was performed under the conditions as follows: a mixture of an aqueous buffer (pH adjusted to 7.8 by 0.03 mol/L ammonia water) and acetonitrile (80∶20, v/v) as mobile phase, paracetamol as the internal standard, and the detection at 230 nm. The linear range was 20-1000 μg/L using the ratio of peak areas; the detection limit was 12 μg/L; the average recovery was (97.11±2.45)%-（104.34±2.17）%， the intra-day relative standard deviations (RSDs) were less than 2.52%, and inter-day RSDs were less than 5.21%.

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Determination of Lactone Components in Chuanxiong by Reversed-Phase High Performance Liquid Chromatography CAO Jianmin, WANG Zonghua, DING Mingyu, YANG Xuedong, KOU Huaijiang 2005, 23 (5):  531-533.  Abstract ( 2047 )   [Full Text(HTML)] () PDF (123KB) ( 838 )   A reversed-phase high performance liquid chromatographic method was developed for the simultaneous determination of four main lactone components including senkyunolide-H, senkyunolide-I, sedanenolide and Z-ligustilide in Chuanxiong, a Chinese herbal medicine. The samples were pretreated using ultrasonic extraction, and 80% ethanol was used as extractant in the experiment. The chromatographic analysis was carried out using an XDB-C8 column and the mobile phase consisted of methanol-1%(volume fraction) acetic acid water (55∶45→100∶0, v/v, in 15 min). The flow rate was 0.8 mL/min. A diode array detector was used to detect the compositions and 280 nm was chosen as the detection wavelength. The whole process could be performed within 15 min. The operating curves were found to be linear over the ranges of 0.4-2.2 mg/L (r=0.9992), 0.4-2.2 mg/L (r=0.9979), 2.6-7.8 mg/L (r=0.9992) and 4.8-14.3 mg/L (r=0.9998) and the detection limits (S/N=3) were 0.024, 0.027, 0.018 and 0.011 μg for senkyunolide-H, senkyunolide-I, sedanenolide and Z-ligustilide, respectively. The recoveries of the four lactone components were found in the range of 96%-108%. The rapid and accurate method has been successfully applied to the simultaneous determination of the four lactone components in Chuanxiong.

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Isolation, Purification and Identification of Geniposidic Acid in Eucommia ulmoides Oliv. by Silica Column Chromatography, Reversed-Phase High Performance Liquid Chromatography, Liquid Chromatography-Electrospray Ionization Mass Spectrometry and Nuclear Magnetic Resonance CAO Hui, CHEN Xiaoqing, XIAO Jianbo, TANG Zhaoqi, OUYANG Dongsheng 2005, 23 (5):  534-537.  Abstract ( 1995 )   [Full Text(HTML)] () PDF (160KB) ( 833 )   The methods using silica column chromatography, reversed-phase high performance liquid chromatography, liquid chromatography-electrospray ionization mass spectrometry and nuclear magnetic resonance (RP-HPLC/LC-ESI-MS/NMR) for the isolation, purification and identification of geniposidic acid (GPA) in Eucommia ulmoides Oliv. were established. The crude extract of E. ulmoides was obtained after E. ulmoides was extracted with 70% ethanol and the extract was concentrated under reduced pressures. The obtained crude extract dissolved in methanol was injected to a silica gel column and eluted with chloroform-methanol. The eluted fractions were analyzed by RP-HPLC. The eluant from chloroform-methanol (8∶1, v/v) was indicated to be a single component by HPLC with a retention time of 5.142 min. The HPLC analysis of the mixture of this fraction with a GPA standard resulted in a single peak. The ultraviolet and infrared spectra of the eluted solution were essentially the same to those of GPA. On the other hand, LC-ESI-MS, 1H- and 13C-NMR experiments also indicated that the fraction was identical to GPA.

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Simultaneous Determination of Water-Soluble Vitamins C, B1, B2 and B6 in Almonds by High Performance Liquid Chromatography SHEN Yehua, ZHANG Ping, KONG Xianghong, GUO Chunhui, WANG Jiwu 2005, 23 (5):  538-541.  Abstract ( 2005 )   [Full Text(HTML)] () PDF (161KB) ( 871 )   A method has been developed for the simultaneous determination of four water-soluble vitamins C, B1, B2 and B6 in almond by high performance liquid chromatography. The contents of vitamins C, B1, B2 and B6 in almonds in Pucheng County, Shaanxi Province were determined under optimized conditions as follows. In the first step, the sample was prepared by acid hydrolysis. In the second step, the separation was performed on an Inertsil ODS-3 column (25 cm×4.6 mm i.d., 5.0 μm) with a mobile phase of 0.05 mol/L KH2PO4 (pH 6.0)-methanol (70∶30, v/v) and a detection wavelength at 265 nm. The linear ranges of four vitamins were within 5.0-50.0 mg/L (r=0.9990-0.9997). At the spike level ranged between 5.0-20.0 mg/kg, the average recoveries of the four vitamins in the Pucheng almond ranged from 91.77% to 99.30% with relative standard deviations between 0.31% and 1.98%. For vitamins B2 and B1, the contents were found to be 4.27-4.53 mg/kg and 0.799-0.838 mg/kg, respectively, while vitamins C and B6 were not discovered in Pucheng almonds. The method is simple, rapid, reproducible and accurate.

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Simultaneous Determination of Sudan Red Dyes in Foods by High Performance Liquid Chromatography with a Clean-Up Procedure by Gel Column XIE Weiping, HUANG Yingyu, FU Huirong, HU Guilian 2005, 23 (5):  542-544.  Abstract ( 2012 )   [Full Text(HTML)] () PDF (129KB) ( 937 )   A method was developed for the simultaneous determination of Sudan Red Ⅰ, Ⅱ, Ⅲ and Ⅳ in foods by high performance liquid chromatography (HPLC) with a clean-up procedure by gel column. Sample was extracted from foods with ethanol. The extract was cleaned up with a Bio-Beads SX3 gel column (200 mm×10 mm i.d.) and eluted with cyclohexane-ethyl acetate (1∶1, v/v). The analysis was performed on a Symmetry Shield RP18 column (250 mm×4.6 mm i.d., 5 μm) with 100% methanol as the mobile phase at a flow rate of 1.5 mL/min, detection at 478 nm and confirmation by diode-array spectra. All of the four compounds demonstrated good linear relationship (r>0.999) in the range of 0.1-10.0 mg/L. The limits of detection (LOD) were from 7 to 14 μg/kg. The average recoveries for all four dyes (spiked at the levels of 0.25 and 2.5 mg/kg) in chili sauce and sausage ranged from 80.7% to 96.3%, and the relative standard deviations were from 2.4% to 5.9%. The method is sensitive, reliable and can be applied for the analysis of four Sudan Red dyes in foods.

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Determination of Phenylarsenic Compounds in Environmental Samples by High Performance Liquid Chromatography LI Shanmao, LI Wei, YUE Lijun, ZUO Boli 2005, 23 (5):  545-547.  Abstract ( 1892 )   [Full Text(HTML)] () PDF (128KB) ( 712 )   A reversed-phase high performance liquid chromatographic method was developed for simultaneous determination of phenylarsonic acid (PAA), phenylarsine oxide (PAO), diphenylarsinic acid (DPAA), bis(diphenylarsine)oxide (BDPAO) and triphenylarsine (TPA) in soil samples. The extraction solvent for soil samples was acetonitrile and ultrasound was used in the extraction. Good separation was achieved by using an Inertsil CN-3 column (250 mm×4.6 mm i.d., 5 μm) with the following conditions: gradient program of mobile phase, a 10 min linear gradient from 100% A (a mixture of acetonitrile-2.5 g/L KH2PO4 (pH 2.0) buffer (5∶95, v/v) ) to 100% B ( a mixture of acetonitrile-2.5 g/L KH2PO4 (pH 2.0) buffer (50∶50, v/v) ), and isocratic at 100% B from 10.01 min to 28 min; flow rate of 1.0 mL/min; time-programmed UV detection at 210 nm (0-10.5 min, 20-28 min) and 268 nm (10.5-20 min). The linear range of PAA, PAO, DPAA, BDPAO and TPA were 8-30, 5-40, 20-4000, 120-8000 and 1-60 mg/L, respectively. The detection limits at a signal-to-noise ratio of 3 were 0.1, 0.1, 0.2, 10, and 0.1 mg/L for PAA, PAO, DPAA, BDPAO and TPA, respectively.

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Analysis of Volatile Oil of Garlic by Gas Chromatography-Mass Spectrometry GUO Xiaofei, DU Ailing, GUAN Congsheng, PAN Guangmin, DU Aiqin, WANG Weiqiang 2005, 23 (5):  548-550.  Abstract ( 2385 )   [Full Text(HTML)] () PDF (114KB) ( 800 )   The volatile oil of garlic was extracted by hydrodistillation method and gas chromatography-mass spectrometry was applied to analyse the compounds in the oil. The best extraction conditions for high-content, effective components were obtained through optimization. The capillary column was an HP-5MS column (25 mm×0.25 mm i.d.×0.25 μm); oven temperature increased with a rate of 5 ℃/min from 80 to 300 ℃, and then maintained for 20 min; sample size of 1 μL; split ratio of 100∶1; carrier gas of helium (1 mL/min). Mass spectra were obtained at 70 eV. The temperatures of injector base, ionization source were maintained at 270 ℃, 230 ℃ respectively. Under these conditions, twenty compounds in the volatile oil of garlic were isolated and identified, and the content of each was determined. Sulfur-containing compounds were found to be the principal components, of which the major compound was diallyl trisulfide with the content of more than 30%, which is higher than the others in the literature. The experimental results also indicated that hydrodistillation method is an effective method for officinal component extraction. In addition, it was also demonstrated that the garlic volatile oil was stable when stored at 0 ℃ for 6 months.

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Determination of the Dissociation Constants of Basic Compounds by Reversed-Phase High Performance Liquid Chromatography on C12-Zirconia ZHANG Qinghe, ZHANG Weibing, LI Tong, ZHANG Yukui 2005, 23 (5):  551-554.  Abstract ( 2040 )   [Full Text(HTML)] () PDF (167KB) ( 673 )   The high performance liquid chromatographic (HPLC) behavior of aromatic amines and pyridine derivatives was studied on a new reversed-phase stationary phase, C12-alkyl-modified zirconia. The effects of mobile phase variables such as methanol content and pH were investigated. The results showed that the stationary phase was stable in the mobile phase with a pH range of 2-12. It was found that on the new stationary phase the bases demonstrated the “traditional” behavior of retention due to their hydrophobicity. The retention factors of these basic compounds on the stationary phase increased rapidly with pH from pH 2-7, and then increased slowly until reaching a constant value. The dissociation constants (pKa) of 13 basic compounds were determined based on the relationship between their retention factors and the pH of mobile phase. Compared with references, the errors of the pKa values obtained by this HPLC method were within 0.35 pH units.

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Thin Layer Chromatographic Study of Bauxite and Quantitative Estimation of Co-Existing Al3+, Fe2+ and Ti4 MOHAMED NAJAR P A, JEURKAR J U, RAMANA RAO K V 2005, 23 (5):  555-561.  Abstract ( 1627 )   [Full Text(HTML)] () PDF (274KB) ( 540 )   Thin layer chromatography in combination with spectrophotometry and titrimetry has been used to evaluate chromatographic characteristics of bauxite constituents. The retention behaviors of four major constituents (Al3+, Fe2+, Ti4+, Si4+) in bauxite mineral have been examined on plain and modified layers of silica gel G, silica gel H and cellulose with mobile phases containing aqueous sodium chloride, formic acid and hydrochloric acid. Ternary separation of Al-Fe-Ti was achieved on chromatographic plates made of silica gel H. The pH effect and presence of impurity elements in samples, nature of stationary phases on the ternary separation and detection limits of bauxite constituents were studied. Silicon in bauxite was detected on cellulose plates. Quantitative determinations of Al3+, Fe2+ and Ti4+ on silica gel H impregnated with sodium formate layers were achieved by titrimetry and spectrophotometry.